1. Field of the Invention
The present invention relates generally to a positioning device for maintaining a patient in an optimal prone position during a back surgery and, more particularly, to a dynamic positioning device which allows the surgeon to apply and adjust individual corrective forces to the patient's trunk at any time during the surgery.
2. Description of the Prior Art
Positioning of the patient is an important consideration in back surgery. Initially patients were simply placed faced down with their stomachs pressed on the operating table. It has been found that when a patient lies on his or her stomach in a prone position, added pressure is induced on the inferior vena cava, resulting in increased bleeding. It was later found that blood loss could be reduced by supporting the patient in a prone position with the abdomen pendulous and free.
Current devices used in operating rooms for supporting patients in a prone position with the abdomen pendulous and free are passive devices designed only to provide support to the patient's trunk on the operating table during the surgery in order to avoid pressure sores of the skin over bony prominences and/or hemorrhage during prolonged surgeries. The most frequently used device is the Relton-Hall frame which is a four poster passive support under the iliac crests and the upper thorax below the clavicles. Tables similar to the Relton-Hall frame are sometimes referred to as four posts, chest roll, and the Jackson table. It has been demonstrated that such passive frames can provide some changes in spinal configuration by virtue of the gravity effect. Studies have also shown that the position of the patient during scoliosis surgery is a critical step that may significantly affect the post-operation results.
During surgical correction of a spinal deformity, the surgeon has to perform manipulation on the spine with various surgical instruments in order to obtain the best possible correction; it would be desirable to have a positioning device that could actively help the surgeon to perform these corrective maneuvers, by applying corrective forces on the thorax of the patient. To the applicant's knowledge, there are currently no such positioning devices for operating tables that can provide active correction of a spinal deformity during surgery for a spinal deformity.
Existing positioning devices also present some limitations at the level of the initial positioning of the patient in that the patient positioning pads can only be roughly adjusted to the morphology of the patient.